I am running a Twonky Server from twonky.com on my MAC OS X El Capitan. It works just fine in the local network but the computer is also connected to a VPN network and has an additional IP address on the virtual VPN network interface. While all other services run that MAC are available over VPN the TwonkyServer seem to listen only to the local IP address. I ruled out trouble with firewall or routing already, it must have something to do with the configuration of the service itself.